package demo16;

public class Test {

    public int peakIndexInMountainArray(int[] arr) {
        int left = 1, right = arr.length - 2; //由题分析出左右第一个位置一定不是峰值。
        while (left < right) {
            int mid = left + (right - left + 1) / 2;
            if (arr[mid] > arr[mid - 1]) left = mid;
            else right = mid - 1;

        }
        return left;
    }

    public int findPeakElement(int[] nums) {
        int left = 0, right = nums.length -1;
        while (left < right) {
            int mid = left + (right - left) / 2;
            if (nums[mid] < nums[mid + 1]) left = mid + 1;
            else right = mid;
        }
        return left;
    }

}
